Place the bread in a 350° oven to dry for 15 minutes. Cook bacon until crispy and set aside. Add two tablespoons of butter to remaining fat to cook leeks with the celery until soft, about 10 minutes. Add apples, chestnuts, parsley and thyme to cook for an extra 5 minutes. Toss in bread, chopped bacon and cream. Add salt and pepper and mix well to make sure bread soaks in the cream. Place on a shallow baking dish and bake for 30 minutes at 350°.